1. Field of the Invention
The present invention relates to an angle measurement apparatus for measuring an angle between a holder holding a substrate and an ion beam, and an actual implantation angle of the ion beam, etc., the angle measurement apparatus being used for an ion implanter. The present invention also relates to the ion implanter having the angle measurement apparatus, and a beam divergence measurement apparatus for measuring a divergence of the ion beam.
2. Description of the Related Art
A related art ion implanter, for example, as described in JP-A-2001-143651 (paragraphs 0002-0007, FIG. 5), uses a front Faraday unit (multipoint Faraday cup) capable of being elevated and lowered, the Faraday unit being arranged on an upstream side of a holder holding a substrate, and also uses a back Faraday unit (multipoint Faraday cup) which is arranged on a downstream side of the holder, in order to measure an angle of an ion beam in a traveling direction. The front Faraday unit is elevated or lowered not only for the measurement using the front Faraday unit, but also so as not to become an obstacle during an ion implantation into a substrate or measurement by the back faraday unit.
On the other hand, an angle of the holder has been measured with an encoder coupled to the holder.
In some related art examples, there are following problems:
(1) An ion beam is projected onto a Faraday cup and an angle of the ion beam is measured. Thus, particles (contaminants) are produced from the Faraday cup during the measurement, which is likely to contaminate a substrate.
(2) An elevating Faraday cup is used. Thus, the Faraday cup has a complicated structure, and the measurement takes long time since the elevation of the Faraday cup requires time.
(3) An angle of a holder and an angle of the ion beam are measured, not being correlated with each other. Thus, an angle between the holder and the ion beam can not be measured accurately.
(4) In an ion implantation state where the ion implantation into a substrate is performed, the front Faraday unit has to be removed from a beam line, as mentioned earlier. Thus, it is not possible to measure the ion beam in the ion implantation state with the front Faraday unit.